@Jarrod1937Jul 17.2010 — #Php has a sleep() function, but 8 hours is too long for a script to run. I'd recommend using something like a cron job (or a scheduled task for windows) to call the script.
@tirnaJul 17.2010 — #provided you have access to create cron jobs on the web server, whether that server is your computer or not, you can set cron jobs to execute php scripts at virtually whatever time intervals you want.